Low Voltage on 3.3V and 5V Pin

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Joined: 28 Mar 2018, 21:27

Low Voltage on 3.3V and 5V Pin

Postby vik123 » 28 Mar 2018, 21:35

I recently soldered my own VESC 4.12. I was able to flash the bootloader on the microcontroller, but when I try to power the vesc or connect it via USB there is no sign of life (no usb, no blue led). The lab power supply is set to 12V and max. current of 0.3 A.

When I measure the pins of 3.3V and 5V on the vesc it shows me actually only around 1.3V (on 3.3V-Pin) and 1.8 V (on 5V-Pin). And around 1 mA from the supply.

I have no idea what is the reason. Perhaps some of you guys?


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Joined: 26 Dec 2015, 14:38
Location: Sweden, Stockholm

Re: Low Voltage on 3.3V and 5V Pin

Postby arvidb » 30 Mar 2018, 15:08

If the board only draws 1 mA the problem cannot be a short of the supply. It's part of the DRV chip that converts the battery voltage to 5 V, so probably you have a problem with that part of the circuit. Check the DRV page in the schematic and inspect your board around that part - i.e. DRV pins 1-4 and 50-57. Check for shorts, wrong component values, etc. Are you sure the bottom GND + thermal relief pad of the DRV got soldered correctly?

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Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: Low Voltage on 3.3V and 5V Pin

Postby rew » 04 Apr 2018, 20:42

If DRV gnd is unsoldered, the 5V will be higher than normal.

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Joined: 09 May 2018, 20:08

Re: Low Voltage on 3.3V and 5V Pin

Postby Duo420 » 09 May 2018, 20:09

You must solder the pad underneath. It's written in the datasheet of the drv8302

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